International cooperation and Kantian moral behaviour: complements or substitutes?

Faced with a global emissions problem such as climate change, we know that if countries’ emissions decisions are made in an independent and self-interested fashion the outcome can be very far from optimal. One proposed solution is to have countries enter international environmental agreements (IEAs) whereby individual countries’ emissions decisions are taken in the interests of all the participating countries and so reflect a degree of altruism. However, if the decision to co-operate is made in a self-interested fashion the standard non-cooperative model of IEAs yields the pessimistic conclusion that the more serious the environmental problem the smaller will be the equilibrium membership of an IEA. Our paper examines the implications for emissions, IEA membership and welfare of assuming that countries make both emissions and IEA membership decisions in the alternative moral fashion of acting as imperfect Kantians as defined by Alger and Weibull (2013). We show that (i) the first-best can be achieved when countries either act as Perfect Kantians or by fully cooperating; (ii) in a more imperfect setting, these two forms of moral behaviour are complementary approaches to improving welfare outcomes in the sense that the greater the weights on Kantian behaviour the larger is the equilibrium coalition; (iii) the weights on Kantian behaviour that will induce full cooperation and hence the first-best are significantly less than 1; (iv) for given Kantian weights, our model generates higher equilibrium IEA membership, lower emissions and higher welfare than in the related paper by Eichner and Pethig (2022: 'International environmental agreements when countries behave morally') which, we argue, does not fully capture the benefits of membership decisions.